The role of angular momentum transfer to determine the mass ratio of binaries

A thermodynamical approach to the problem of star formation, presented in a previous paper shows how the characteristics of the outcome depend on the initial conditions (thermal and rotational energies) and on the distribution of the angular momentum among the various parts of the system when the last stages of collapse are assumed as adiabatic. In case of a binary outcome the distribution can be expressed in terms of two parameters roughly corresponding to a) the spin ratio as function of the mass ratio and b) the fraction of angular momentum involved in the orbital motion. A systematic exploration of these parameters allows to analyze the different types of results. Some preliminary results are presented assuming that both single and binary outcomes have an equilibrium McLaurin ellipsoidal shape not, however, taking into account the possible formation of a system star+protoplanetary disc. (author). 3 figs., 4 refs